I think you didn’t look at the image long enough to understand the point.

What the image seems to be trying to convey (albeit in a confusing way) is the perception a kid would have if you offered him a salary of $400 a week, that he’d be imagining he could buy a huge house and have fancy cars, whereas an adult would supposedly think they’d only be able to afford a lowly hovel at the same wage.

Otherwise, it just doesn’t make sense, as the alternative interpretation (which you seem to have chosen) is that “kids” and “adults” get charged different amounts of rent based solely on that distinction.

tl;dr- $400 /wk is not the cost of pictured items, but the perception of what can be purchased by 2 different groups of people on a given wage.